We loved staying at Tib's place!
Punnawithi is a bit far from the downtown area, but we knew that and didn't mind because her place is close to the BTS station (less than 10 minute walk), and you can get to Asok in no time!
For the price you'd pay for a subpar place in Asok or Sukhumvit, you get a very large and comfortable bed, clean bathroom with hot water, modern condo with security guards, and a peaceful neighborhood with a 7-11 on the corner.
Check-in is simple where the security guards help you settle in. Wifi is superb, and there is even a TV where you can hook up to with HDMI. The fridge and AC were both excellent and in working condition. The general feel of the apartment is luxurious and spacious. I was very happy with the apartment!